Screed extension assembly for asphalt paving machine

ABSTRACT

Disclosed are interlocking extension units for extending the screed of an asphalt paving machine. Each extension unit has an open inner end having two rotatable shafts extending vertically there across. A cylindrical cam is welded to each of the shafts in an off-center position. Disposed about each of the cams is a steel ring having a bolt extending radially therefrom beyond the inner end of the unit, the bolt being adapted to be connected to a slotted plate in the outer end of an adjacent unit. Also protruding from the inner end of each unit are two adjustable guide studs each of which is adapted to mate with the slotted plate to facilitate alignment of adjacent units and provide a limiting surface against which an adjacent unit is drawn when the cams are rotated.

United States Patent Birtchet et al. 1 Jan. 23, 1973 s41 SCREED EXTENSION ASSEMBLY FOR 3,673,930 7/1972 Birtchet ..94/45 R ASPHALT PAVING MACHINE Primary Examiner-Nile C. Byers, Jr. [75] inventors 3 Attorney-Christensen & Sanborn [73] Assignee: Schneider-Simpson, lnc.,- Tacoma, ABSTRACT wash- Disclosed are interlocking extension units for extend- [22] Filed: Aug. 11, 1971 ing the screed of an asphalt paving machine. Each extension unit has an open inner end having two rotata- PP- N05 170,752 ble shafts extending vertically there across. A cylindrical cam is welded to each of the shafts in an off-center s2 U.S. Cl. ..94 45 R Dispsed each Cams is a Steel Int Cl Eolc {9/22 ring having a bolt extending radially therefrom beyond the inner end of the unit the bolt being adapted to be [58] Field of Search ..94/45, 44, 39, 48 connected to a slotted plate in the outer end of an ad jacent unit. Also protruding from the inner end of [56] Reerences Cited each unit are two adjustable guide studs each of which UNITED STATES PATENTS is adapted to mate with the slotted plate to facilitate alignment of adjacentunits and provide a limiting sur- 2,945,427 7/[960 Gerk ..94/45 R face against which an adjacent unit is drawn when the 3,125,935 3/1964 McCandless... .....94 45 R Cam's are rota,

3,l55,02l ll/l964 Sauer ..94/45 R 3,415,173 l2/l968 Paul ..94/45 R 12 Claims, 7 Drawing Figures PATENTEU JAN 2 3 I973 SHEET 1 OF 2 SCREED EXTENSION ASSEMBLY FOR ASPHALT PAVING MACHINE BACKGROUND OF THE INVENTION This invention relates to screed extension units for asphalt paving machines.

Asphalt paving machines are in common use throughout the construction industry. Such machines typically include an initial leveling surface referred to as a screed for leveling the asphalt which is then compacted while it is at an elevated temperature. Asphalt paving machines are typically heavy and slow-moving and therefore are usually trucked to construction sites. Due to load width limitations on many highways, the paving machines usually must be constructed to widths which are less than the desired width of the strip of asphalt to be laid. Various types of extension units are therefore required in order to extend the screed to the desired width for a given operation. By constructing the paving machine to a width corresponding to a minimum width of a road project and then adding extension units of varying lengths, the paving machine can be adjusted on location to lay a strip of asphalt to any desired width.

A problem has existed in the art in connection with extending the width of the screed assembly in that the screed extension operation typically requires several hours to perform. In some assemblies the services of a welder are required while in other cases the required extensive mechanical modifications necessitate the presence of skilled mechanics to perform the screed extension operation.

The screed extension units disclosed hereinafter are somewhat similar to those disclosed in the commonly assigned US. application of Ralph D. Birtchet, Ser. No. 46,309, filed June 15, I970 now US. Pat. No. 3,673,930. The units of this invention, however, represent a marked improvement thereover in that they are less expensive to manufacture, can be more easily interconnected with other similar units and provide a more rigid, stable screed extension assembly when so interconnected.

SUMMARY OF THE INVENTION In accordance with this invention the screed extension units have the general configuration of channellike steel assemblies having rectangular cross sections and hollow interiors. Thus, the assemblies resemble open-ended right rectangular parallelograms similar to open-ended rectangular boxes. Extending vertically across the interior of each unit adjacent its inner end are positioned two spaced-apart, rotatable shafts, to each of which a cylindrical cam is secured in an offcenter position. Associated with each of the cams is a tensioning means comprised of a steel locking ring disposed about the cam and a tensioning bolt protruding radially outward from the locking ring beyond the inner end of the unit. Also protruding from the inner end of the unit are two guide studs positioned adjacent to the respective tensioning means. On each of the tensioning bolts and guide studs there is situated at least one nut or other head member, the positions of which relative to the open end of the end of the unit are adjustable. Situated at the outer end of the unit are two spaced-apart plates, each having two slots therein adapted to respectively receive a tensioning bolt and a guide stud of an adjacent unit. When the shafts are rotated, the rotation of the cams urges the locking rings inwardly of the unit serving to pull the adjacent unit into a tight engagement therewith. The guide studs provide initial alignment of adjacent units during the interconnection operation. As the units are drawn together by rotation of the two shafts, the slotted plates of the one unit come to bear against the nuts on the guide studs of the other unit. The positions of the nuts can be adjusted such that exact alignment and rigid interconnection of adjacent units can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a portion of a conventional asphalt paving machine having three screed extension units of this invention secured to one side thereof.

FIG. 2 is a plan view with sections removed showing a first pair of interconnected extension units and a third extension unit about to be coupled thereto.

FIG. 3 is a .view of an extension unit taken along line 33 of FIG. 2.

FIG. 4 is an isometric view of portions of two interconnected units showing a locking assembly according to this invention.

FIG. 5 is an exploded isometric view of the locking assembly of FIG. 4.

FIG. 6 is a section view along line 6-6 of FIG. 2.

FIG. 7 is an isometric view of one pair of the lower plate adjustment members on two adjacent extension units.

DETAILED DESCRIPTION OF THE DRAWINGS In FIG. 1, there is shown generally at 10 a portion of the screed of a conventional asphalt paving machine. Such machines per se are well known in the art and are typified by those manufactured by the Barber-Greene Co. A detailed description of the machine is not included herein, since the present invention relates to the extension units ll, 12 and 13 shown as connected to the slightly modified end of the screed. The units 11, 12 and 13 are identical with the exception that unit 11 has an end plate 14, secured thereto by bolts 15, 16 17 and 18 which engage the threaded holes 15A, 16A, 17A and 18A on the plates 19, 20, 21 and 22 at the outer end of each unit (FIG. 3).

As can best be seen in FIG. 3, each extension unit is comprised ofa lower channel member 30 and an upper channel member 31, the latter having offset lower sides at 31A and 31B so that the units can be interconnected to form anelongated 'body member having a rectangular cross section and an open interior. As best seen in FIGS. 2 and 3, the lower and upper channel members 30 and 31 are provided with four interior plates 30C and 31C which are welded thereto. Threaded studs 34, having locknuts 34A disposed on opposite sides of plates 30C and 3 1C, pass through holes in the plates. When tightened, the nuts provide a means to rigidly interconnect the lower and upper channel members 30 and 31 to provide the main body of the extension unit. Since the extension units are hollow, hot gases for heating the asphalt can be circulated inside the units. It will, of course, be evident that units of varying lengths can be fabricated to permit the assembly of a plurality of standard units to achieve a desiredlength of screed extension.

As seen in FIGS. 1 and 2 the extension units are adapted for interconnection to each other. For the purpose of explanation the end of a unit adapted for connection to the paving machine as shown in FIG. 1 is referred to herein as the inner end while the opposite end is referred to as the outer end.

Referring to FIGS. 1-5, two spaced apart, rotatable control shafts 35 and 36 extend vertically across the interior of the extension unit near the inner end thereof. Welded near the bottom of the shafts are cam members 61 and 62. The cams are circular in cross section but are welded to the shafts 35 and 36 in an off-center or eccentric position. Disposed about the cams are locking rings 51 and 52, each of which has a threaded tensioning bolt 53 and 54 welded thereto and protruding radially therefrom beyond the inner end of the unit. On each of these bolts there are two nuts 55A and 55B and a washer 55C. Upon rotation of the handles 37 and 38 secured to the upper ends of the shafts 35 and 36, the earns 61 and 62 rotate, causing the locking rings 51 and 52 and bolts 53 and 54 to move inwardly or outwardly from the interior of the extension unit, depending upon the direction of rotation of the handles. It will be noted that the locking ring 51 and 52 are prevented from falling away from the cams by the bearing blocks 28 and 29, into which the bottom ends of the shafts 35 and 36 are rotatably inserted.

Protruding beyond the inner end of the unit adjacent the connection bolts 53 and 54 are two threaded guide studs 67 and 68. Each of the studs is engaged at one end with threaded holes in support plates 65 and 66 welded to the bottom and sides of the interior of the unit. Nuts 67A and 68A are fixed on the studs by pins extending through the nuts and into the studs (FIG. 5). The spacings between nuts 67A and 68A and the inner end of the unit can be adjusted by varying the amount by which studs 67 and 68 extend through plates 65 and 66 and then locking the studs in place by means of nuts 67B and 688.

The outer end of each extension unit is provided with two heavy, inwardly extending plates and 22 welded to the interior side and bottom surfaces. These plates have elongated slots 20A and 22A and upwardly open slots 20B and 22B. The slots 20A and 22A are adapted to receive the guide studs 67 and 68, while the slots 20B and 22B are adapted to receive tensioning bolts 53 and 54.

Referring to FIGS. 2 and 3, it will be seen that each of the shafts 35 and 36 has welded beneath the handle thereof 37 and 38 a small rectangular plate 37A and 38A. Each of these two plates has ahole therein so that locking pins 47 and 48 can be dropped through the holes and into one of the holes 49 in the upper surface of the extension unit. The holes 49 are preferably threaded and hence bolts can be used as pins 47 and 48 for locking the handles 37 and 38 in their respective locked positions after the interconnection of adjacent extension units has been accomplished.

ln coupling one unit to a preceding unit, the handles 37 and 38 of the succeeding unit are rotated to their unlocked positions with the tensioning bolts 53 and 54 turned inwardly of the unit so as not to interfere with initial coupling of the units. The succeeding unit is then initially connected to the preceding unit by means of the hinged plate 74 welded to the top surface of the inner end of each unit. Each plate 74 is hinged at 75 and is provided with an elongated hole 74A adapted to loosely encompass the vertical stud 76 extending upwardly from the top surface of the outer end of each extension unit. As the units are initially connected as just described, the guide studs 67 and 68 are inserted in slots 20B and 22B to provide initial alignment between the units. Once the units are thus interconnected, the

worker is. relieved of the strain associated with lifting the relatively heavy extension unit while the coupling operation is completed. By reaching through the outer end of the succeeding unit, the worker then rotates the locking rings 51 and 52 such that the tensioning bolts 53 and 54 rest in slots 20B and 228 in plates 20 and 22 of the preceding unit, with the nuts and washers on the bolts being on the interior sides of the plates. After the nuts on the tensioning bolts have been tightened down by hand against the plates, the handles 37 and 38 are rotated so as to rotate earns 61 and 62, thereby urging the rings 51 and 52 and bolts 53 and 54 toward the interior of the succeeding unit and drawing the two units together. The effective lengths of the tensioning bolts and guide studs of the succeeding unit (i.e., the positions of the nuts thereon relative to the inner end of theunit) should be adjusted such that, when'the handles are rotated to their locked positions, the bottom edges of the units firmly abut against each other along their lengths and the plates 20 and 22 are forced against the guide stud nuts 67A and 68A with considerable pressure. The guide stud nuts thus serve as limit stops against which the cams operate. The clamping or wrenching action exerted on plates 20 and 22 by the tensioning bolts nuts and the guide stud nuts assures that the adjacent units are rigidly interlocked against relative movement. Any suitable lever such as a length of pipe placed over the handles 37 and 38 can be used to exert the substantial pressure by the earns 61 and 62 to firmly lock the adjacent units together. If the positions of the nuts on the connecting bolts and on the guide studs are such that proper alignment and rigid interconnection of the units are attained when the handles are rotated, the lockpins 47 and 48 are then dropped or threaded into position to lock the handles. If a perfect interconnection has not been obtained, the handles are rotated to their unlocked positions and the effective lengths of one or both the tensioning bolts and/or one or both of the guide studs can be adjusted as described above.

It willbe observed that the lower front and lower rear edges of each extension unit are curved as seen at 30F and 30R. The reason for this is that if one assumes that the edge 30F is initially used as the front of the screed surface, it will be found that the bottom surface of the extension unit will gradually wear in a front-to-rear direction due to movement of the extension unit over the asphalt surface. Eventually the surface would wear to the point where repair or replacement would be required. With the units shown herein having two screed surfaces 30F and 30R extending upfrom the bottom surface, the useful life of each extension unit is effectively doubled in that a given extension unit can be removed from the left hand side of a machine as illustrated in the drawings and connected to the right-hand side of the machine; Thus, the rear surface 30R now becomes the front surface when positioned on the 0pposite side of the machine.

The extension unit for the machine should present a bottom surface which is coplanar with the screed surface being extended. When wear occurs as described above, transfer of an extension unit to the opposite side of the machine can result in a slight elevation differential between the adjacent surfaces of interconnected screed extension units and/or the main screed and it would be advantageous to be able to bring the surfaces into alignment. For this reason each of the screed extension units includes four adjustment devices 81, 82, 83 and 84 (FIGS. 2, 3 and 7). The adjustment devices 81 and 82 are identical and are located at the outer end. Adjustment devices 83 and 84 are also identical and are located at the inner end. FIG. 7 shows the construction details of these adjustment devices most clearly. The device 84 is formed of a heavy parallelogram of steel welded to the interior of the screed extension unit. The extended portion 84A overlies the bottom edge of a preceding unit. The bolt 85, which is threaded in nut 86 welded to the portion 84A, passes through 84A and engages the edge of the bottom of the adjacent extension unit. The device 82 comprises a hollow rectangular body 87 welded to the bottom of the unit. A movable block 88 fits inside of the body 87 and carries a bolt and nut assembly 89-90 similar to the bolt and nut assembly 85-86. The locking bolt 91 serves to lock block 88 in position, the arrangement being such that a block 88 can easily be removed or retracted inside body 87 when a given extension unit is the last one in an assembly and has an end plate 14 secured thereto (FIG. 1 When the bolts 85 and 89 are adjusted, they serve to exert pressure on the surface of the bottom portion of the adjacent unit and hence permit forcing the adjacent surfaces into exact alignment.

As will be appreciated by referring to FIG. 3, the end of the main screed portion of an asphalt paving machine can be readily modified to have a set of plates corresponding to plates and 22 to facilitate securement of the first extension unit to the asphalt paving machine. However, it has been found convenient to simply weld to the main screed either a complete unit or the inner or outer end portion of a unit to the machine to serve as an anchor for the first extension unit.

What is claimed is:

1. An extension unit for the screed of an asphalt paving machine comprising in combination: a body member having a hollow interior, a first open end, and a substantially fiat bottom plate; a first rotatable shaft extending across the interior of said body member adjacent said first open end; first cam means including a first eccentric secured to said first shaft; first tensioning means including a first ring member disposed about said first eccentric and a first tensioning rod secured to said first ring member, and protruding beyond said first open end, said first tensioning rod being adapted to be coupled to another extension unit and to be urged toward the interior of said body member when said first eccentric is rotated, thereby pulling said body member into engagement with said other unit; and a first stud member secured to said body member adjacent said first open end and defining a first limit surface adapted to abut against said other unit, said first stud member being adjustable to selectively position said first limit surface relative to said first open end.

2. The extension unit of claim I wherein said first tensioning means and first stud member are located proximate said bottom plate.

3. The extension unit of claim 1 wherein said first stud member comprises a stud having a head member thereon intermediate the ends thereof, said head member defining said first limit surface.

4. The extension unit of claim 1 wherein said body member has a second open end, and tensioning rod attachment means secured to and disposed inside of said body member adjacent said second open end.

5. The extension unit of claim 4 wherein said first stud member comprises a stud having a head member thereon intermediate the ends thereof, said head member defining said first limit surface.

6. The extension unit of claim 5 wherein said first tensioning rod attachment means comprises a plate member having openings therein adapted to receive the first tensioning rod and the first stud member of another like extension unit.

7. The extension unit of claim 1 further comprising a second rotatable shaft extending across the interior of said body member adjacent said first open end; second cam means including a second eccentric secured to said second shaft; second tensioning means including a second ring member disposed about said second eccentric and a second tensioning rod secured to said second ring member and protruding beyond said first open end, said second tensioning rod being adapted to be coupled to said other extension unit and to be urged toward the interior of said body member when said second eccentric is rotated, thereby pulling said body member into engagement with said other unit; and a second stud member secured to said body member adjacent said first open end and defining a second limit surface adapted to abut against said other unit, said second stud member being adjustable to selectively position said second limit surface relative to said first open end.

8. The extension unit of claim 7 wherein said first and second tensioning means and said first and second stud members are located proximate said bottom plate.

9. The extension unit of claim 7 wherein each of said first and second stud members comprises a stud and a head member situated on said stud intermediate the ends thereof, said head member defining one of said first and second limit surfaces.

10. The extension unit of claim 7 wherein said body member has a second open end, and first and second tensioning rod attachment means secured to and disposed inside of said body member adjacent said second open end.

11. The extension unit of claim 10 wherein each of said first and second stud member comprises a stud and a head member situated on said stud intermediate the ends thereof, said head member defining one of said first and second limit surfaces.

12. The extension unit of claim 11 wherein said first tensioning rod attachment means comprises a first plate member having openings therein adapted to receive the first tensioning rod and first stud member of another like extension unit and said second tensioning rod attachment means comprises a second plate member having openings therein adapted to receive the second tensioning rod and second stud member of said another like extension unit.

41 a: is 

1. An extension unit for the screed of an asphalt paving machine comprising in combination: a body member having a hollow interior, a first open end, and a substantially flat bottom plate; a first rotatable shaft extending across the interior of said body member adjacent said first open end; first cam means including a first eccentric secured to said first shaft; first tensioning means including a first ring member disposed about said first eccentric and a first tensioning rod secured to said first ring member, and protruding beyond said first open end, said first tensioning rod being adapted to be coupled to another extension unit and to be urged toward the interior of said body member when said first eccentric is rotated, thereby pulling said body member into engagement with said other unit; and a first stud member secured to said body member adjacent said first open end and defining a first limit surface adapted to abut against said other unit, said first stud member being adjustable to selectively position said first limit surface relative to said first open end.
 2. The extension unit of claim 1 wherein said first tensioning means and first stud member are located proximate said bottom plate.
 3. The extension unit of claim 1 wherein said first stud member comprises a stud having a head member thereon intermediate the ends thereof, said head member defining said first limit surface.
 4. The extension unit of claim 1 wherein said body member has a second open end, and tensioning rod attachment means secured to and disposed inside of said body member adjacent said second open end.
 5. The extension unit of claim 4 wherein said first stud member comprises a stud having a head member thereon intermediate the ends thereof, said head member defining said first limit surface.
 6. The extension unit of claim 5 wherein said first tensioning rod attachment means comprises a plate member having openings therein adapted to receive the first tensioning rod and the first stud member of another like extension unit.
 7. The extension unit of claim 1 further comprising a second rotatable shaft extending across the interior of said body member adjacent said first open end; second cam means including a second eccentric secured to said second shaft; second tensioning means including a second ring member disposed about said second eccentric and a second tensioning rod secured to said second ring member and protruding beyond said first open end, said second tensioning rod being adapted to be coupled to said other extension unit and to be urged toward the interior of said body member when said second eccentric is rotated, thereby pulling said body member into engagement with said other unit; and a second stud member secured to said body member adjacent said first open end and defining a second limit surface adapted to abut against said other unit, said second stud member being adjustable to selectively position said second Limit surface relative to said first open end.
 8. The extension unit of claim 7 wherein said first and second tensioning means and said first and second stud members are located proximate said bottom plate.
 9. The extension unit of claim 7 wherein each of said first and second stud members comprises a stud and a head member situated on said stud intermediate the ends thereof, said head member defining one of said first and second limit surfaces.
 10. The extension unit of claim 7 wherein said body member has a second open end, and first and second tensioning rod attachment means secured to and disposed inside of said body member adjacent said second open end.
 11. The extension unit of claim 10 wherein each of said first and second stud member comprises a stud and a head member situated on said stud intermediate the ends thereof, said head member defining one of said first and second limit surfaces.
 12. The extension unit of claim 11 wherein said first tensioning rod attachment means comprises a first plate member having openings therein adapted to receive the first tensioning rod and first stud member of another like extension unit and said second tensioning rod attachment means comprises a second plate member having openings therein adapted to receive the second tensioning rod and second stud member of said another like extension unit. 